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Literature review of baseline study for risk analysis

Environment International 63 (2014) 149–162
Contents lists available at ScienceDirect
Environment International
journal homepage: www.elsevier.com/locate/envint
Literature review of baseline study for risk analysis — The landfill
leachate case
T.E. Butt a,⁎,1, H.M. Gouda c, M.I. Baloch d, P. Paul e, A.A. Javadi b, A. Alam f
Centre of Water Systems (CWS), College of Engineering, Mathematics & Physical Sciences, The University of Exeter, Harrison Building, North Park Road, Exeter, EX4 4QF England, UK
Department of Engineering, College of Engineering, Mathematics & Physical Sciences (CEMPS), The University of Exeter, Harrison Building, North Park Road, Exeter, EX4 4QF England, UK
Department of Geography and Environmental Management, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY England, UK
Utilities Business Unit, Jacobs, 1180 Eskdale Road, Winnersh, Wokingham, RG41 5TU England, UK
School of Engineering and Design, Brunel University, Uxbridge, UB8 3PH England, UK
Sustainable Development Study Center, Government College University, Katchery Road, Lahore, Pakistan
a r t i c l e
i n f o
Article history:
Received 26 January 2013
Accepted 23 September 2013
Available online 30 November 2013
Baseline study
Risk analysis
Risk assessment
Preliminary investigation
Waste disposal sites
Landfill leachate
a b s t r a c t
There is growing awareness and public concern about environmental impacts of waste management and disposal.
Environmental policy instruments have been strengthened and associated governmental programmes have increased in recent years, resulting in high level strategies for waste management. Risk assessment is now an
essential tool in the prioritisation of environmental and human health protection. However, regulators need to
compare the full range of risks on a sound and consistent basis. Comparing risks from such diverse sources
poses a significant challenge, and traditional hazard and risk assessments are no longer sufficient. Consideration
now needs to be given to a much wider range of factors if risk assessment is to be used as an aid to more integrated
decision-making process. For this purpose, baseline study – the foundation of risk assessment – can play a crucial
role. To date limited research has been conducted on the need, parameters, requirements, and constituents of baseline study particularly in the context of how, why, and what information is to be collated in order to render risk
assessments more appropriately integrated and complete. To establish the ‘state-of-the-art’ of baseline study,
this paper comprehensively reviews the literature regarding environmental risk assessment in general terms,
and then proceeds to review work that is specifically related to landfills and landfill leachate, thereby identifying
knowledge gaps and shortfall areas. This review concludes that a holistic baseline study procedure for waste
disposal sites, which risk assessors could use for carrying out risk analyses specifically for landfill leachate, does
not as yet exist.
© 2013 Published by Elsevier Ltd.
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Background . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Landfills and risk assessment . . . . . . . . . . . . . . . . . . . .
Research aims and methodology . . . . . . . . . . . . . . . . . .
Aims . . . . . . . . . . . . . . . . . . . . . . . . . .
Methodology . . . . . . . . . . . . . . . . . . . . . . .
Definitions and scope . . . . . . . . . . . . . . . . . . . . . . . . . .
Baseline study and risk assessment . . . . . . . . . . . . . . . . . . . .
Risk assessment — connection with baseline study in the holism context
Baseline study — in the holism perspective . . . . . . . . . . . . .
Current and future legislation . . . . . . . . . . . . . . . . . . .
Concluding discussion . . . . . . . . . . . . . . . . . . . . . . . . . .
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
⁎ Corresponding author: Tel.: +44 7817139170.
E-mail address: [email protected] (T.E. Butt).
Tel.: +44 7817139170.
0160-4120/$ – see front matter © 2013 Published by Elsevier Ltd.
T.E. Butt et al. / Environment International 63 (2014) 149–162
1. Introduction
1.1. Background
The main driver for improved and increasingly comprehensive environmental legislation in the UK and other European nations is undoubtedly European legislation (see Table 1). From the signing of the Treaty of
Rome in 1957, until the signing of the Maastricht Treaty in 1992, the
European Community was essentially an economic common market
and had no mandate for environmental regulation. Any directive with
an environmental element rested on the principles of either ‘public
health protection’ or ‘harmonisation’ of environmental rules to avoid
market distortion. The Maastricht Treaty officially adopted the objective
of sustainable development as community policy, advocating a high
level of protection of the environment, based on the precautionary principles including the principle of “pollution prevention at source” and the
“polluter pays principle” (Calleja et al., 2004; Luken, 2009; Pearce and
Turner, 1992; Tadhg and Dermot, 2003).
European waste and water management policies were originally
developed to control pollution and protect the environment, which
stimulated infrastructure investment in the waste and wastewater
treatments sectors. Although criticised for its high cost, this succeeded
in reducing concentrations of regulated point-source pollutants. It was
however found that Member States were exploiting inconsistencies
in the legislative text, and that standards set out in the Dangerous
Substances Directive were not being achieved in many instances. Additionally, evidence of increasing pollution of waters (especially groundwater), and the recognition of the need to safeguard the ‘ecological
quality’ of waters led to the revision and integration of the existing
fragmented waste- and water-related legislation (listed in Table 1)
into integrated management frameworks taking an ecosystem-based
approach (Kallis and Buder, 2001). The Landfill Directive and the
Water Framework Directive were published in the Official Journal of
the European Community in 1999 and 2000, respectively. Both of
these became European, and hence national law, in 2003.
1.2. Landfills and risk assessment
In order to protect public health and the environment, risk assessment
has become a dominant public policy tool for making choices based on
limited resources. Having realised the significance and effectiveness of
risk assessment in environmental management, environmental legislation has started to impose risk analysis as a tool for meeting legal requirements associated with waste hazards (Butt et al., 2009; Environment
Agency, 2003a). For instance, to protect groundwater from landfill leachate contamination, risk assessment has been legislatively introduced into
the UK since 1st May 1994, through “Regulation 15 of the Waste Management Licensing Regulations” (SI, 1994a) and the “Groundwater Regulations” (SI, 1998). The Landfill Directive is implemented in England and
Wales through the “Landfill Regulations” (SI, 2002), made under the
“Pollution Prevention and Control (PPC) Act” (England and Wales)
1999. The equivalent legislation, which is called Landfill (Scotland) Regulations, has come out in Scotland as well (SEPA, 2005a, 2005b; SSI,
2000, 2003). It can be inferred from the introduction of all these legislative instruments that the ‘out of sight, out of mind’ concept regarding
wastes is no longer possible or permissible. To achieve the maximum
protection of the environment against the hazards associated with
landfill sites, all potential hazards must be identified and risks associated with them must be assessed.
Landfill is the most widely employed method for disposal of waste
around the world. The majority of municipal solid waste landfills,
including those that previously co-disposed hazardous materials, continue to receive a significant proportion of bioreactive wastes which
produce mainly greenhouse gases and wastewater known as leachate.
Landfill leachate contains organic and inorganic pollutants including
ammonia, heavy metals, humic-acids, persistent synthetic organic
Table 1
Examples of some relevant legislation.
1. Waste Management Licensing Regulations (SI, 1994a, 2005): Under these
regulations, waste management licences are issued by the Environment Agency
to ensure that the authorized activities do not cause pollution to the
environment, harm to human health or serious detriment to local amenities.
2. Groundwater Regulations (SI, 1998, 2009): This environmental legislation is an
environmental protection measure which completes transposition of the
Groundwater Directive (80/68/EEC) and provides enhanced protection for
3. EU Directive on IPPC (Integrated Pollution Control and Prevention) (EU, 1996):
This Directive (‘the IPPC Directive’) enforces a requirement for industrial and
agricultural activities with a high pollution potential to have a permit which
can only be issued if certain environmental conditions are met, so that the
companies will bear the responsibility for preventing and reducing any pollution
they may cause.
4. EC Directive on EIA (Environmental Impact Assessment) (EC, 1985): The Directive
has been applied to the assessment of environmental effects of those public
and private projects which are likely to have significant effects on the
5. Environmental Protection Act, 1990 and Environmental Act, 1995: The 1990
Act places certain obligations on businesses to ensure that their waste is
suitably contained and disposed of in a proper manner. The 1995 Act covers a
wide range of issues which are related directly and/or indirectly to the
environment. This Act is to make provision with respect to contaminated land
and abandoned mines; to make further provision in relation to National Parks;
to make further provision for the control of pollution, the conservation of
natural resources and the conservation or enhancement of the environment;
to make provision for imposing obligations on certain persons in respect of
certain products or materials; to make provision in relation to fisheries; to
make provision for certain enactments to bind the Crown; to make provision
with respect to the application of certain enactments in relation to the Isles of
Scilly; and for connected purposes.
6. Strategic Environmental Assessment (SEA) Directive (ODPM, 2003): The Directive
ensures environmental effects to be taken into account by authorities during the
preparation of plans and programmes in the fields of land-use, transport, waste
and water management, energy, and a range of other sectors. Thus, this
legislation enhances the degree of integration between various sectors rather
than each sector being treated on its own as a separate entity.
7. EC Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora
(The Habitats Directive) (EC, 1992): The EC Habitats Directive promotes the
maintenance of biodiversity by requiring Member States to take measures to
maintain or restore natural habitats and wild species at a favourable
conservation status. The Directive introduces robust protection for those
habitats and species that are of European importance. In applying these
measures Member States are required to take account of economic, social and
cultural requirements and regional and local characteristics.
8. Water Framework Directive — WFD (EC, 2000): The 1980 Groundwater
Directive (80/68/EEC) aims to protect only groundwater whereas the WFD
lead to a major overhaul of water protection legislation
(Burges Salmon LLP, 2009). The WFD commits European Union member
states to protecting and making all water bodies (rivers and lakes), transitional
waters (estuaries), coastal waters and groundwater of good qualitative and
quantitative status by 2015. Thus, this introduces integrated approach
on much larger scale.
9. Landfill Directive (EC, 1999) and Landfill Regulations (Scottish Executive et al.,
2005; SI, 2002): The overall aim of this environmental legislation is to
prevent or reduce as far as possible negative effects on the environment,
in particular the pollution of surface water, groundwater, soil and air, and
on the global environment, including the greenhouse effect, as well
as any resulting risk to human health, from the landfilling of waste, during
the whole life-cycle of the landfill. This legislation also has important
implications for waste handling and waste disposal.
Principles of the Landfill Directive and WFD together aim for:
• The minimum requirement of ‘no deterioration’ for all waters,
• Achieving good ecological and chemical quality status for inland and coastal
waters. Good ecological status can be defined as only a slight departure from
the biological community that would be expected in conditions of minimal
anthropogenic impact. Good chemical status fulfils all the standards set by EU
legislation for the concentration of chemicals in water. Additionally,
more stringent requirements for ‘protected zones’ such as drinking waters,
bathing waters, designated areas for the protection of habitats or species
(including Natura 2000 sites), also other zones may be designated for the
protection of economically significant species or recreational activities.
• Achieving international agreements such as OSPAR and eliminate emissions
of priority hazardous substances, such as heavy metals and PAHs.
T.E. Butt et al. / Environment International 63 (2014) 149–162
pollutants and inorganic salts of high concentration. If landfill leachate is
not collected, treated and discharged safely, it shall become a potential
pollution source which threatens soil, surface water and groundwater
(Butt et al., 2009; Fatta et al., 1999). Therefore, landfill leachate is
recognised as an important environmental problem and its risk assessment and management is thereby considered essential.
Risk assessment, however, is a relatively new and fast developing
science, both in terms of its adoption as a formalised analytical process
applied to environmental issues, and also as a policy tool to assist regulators in the decision making process (Butt et al., 2009; Eduljee, 2000).
This is not just in relation to landfill and other environmental sectors
but also in relation to other areas including ecology, epidemiology,
health and safety, radiation, earthquakes, finance, construction management, building contract selection, insurance, economics, fire, landslides,
ship navigation, the food industry, and the oil industry (Butt and
Oduyemi, 2003; Butt et al., 2006, 2009; CIWEM, 1999). Regardless of
the type of risk assessment needed and the specific environmental
area of its application, a baseline study is the most important component of a risk analysis system (Asante-Duah, 1996; Blight and Fourie,
1998; CIRIA, 2001; Environment Agency, 2003a; ICE, 1994). In this
paper it is this baseline study which is the core focus.
1.3. Research aims and methodology
1.3.1. Aims
The main aim of the paper is to establish knowledge gaps in baseline
study specifically regarding landfill leachate risk assessment, thereby
paving a way for researchers to further research and develop in this
particular area. Hence this paper identifies and critiques the limitations
of existing research literature in this area while simultaneously
establishing the ‘state-of-the-art’ of baseline studies. Further aims in
this work include developing some new insights in how to bridge the
identified knowledge gaps, and the significance of why these gaps
need to be closed. However, as the focus of the paper is primarily to
both review the existing ‘knowledge’ and ‘knowledge shortfalls’ regarding this subject matter, any new insights are only indicatively addressed
for the sake of brevity, and in order to simply present a way forward for
future research work in this area.
1.3.2. Methodology
The basic methodology used to carry out this review study included
the following elements:
1. The systematic selection of specific material used in the literature
review process.
2. The criteria that are set and used to bench-mark the selected literature
3. A review of the relevant environmental legislation.
Initially as a background to the review process, this paper sets the
environmental legislative scene dating as far back as 1957. From that
point onward, the paper describes how the environmental legislation
came into being and has been steadily growing ever since then, both
in terms of becoming more stringent and holistic. The paper next
considers the links between the environmental legislation with risk
assessment, and the significance of baseline studies in risk assessments. In addition, the paper commences the review of literature
from a broad prospective covering various business fields, both
environment-related and non-environment-related (e.g. insurance
and construction management sectors). Then the paper narrows the
review down to contaminated land in which landfills are deemed as a
specific type of land contamination. After this, the paper then further
narrows down the focus on to the main issue in this study which is landfill leachate.
Following on from the above, a brief but clear list of a wide range of
features that can make a baseline study more holistic are discussed (for
a more integrated and unified risk assessment of landfill leachate). The
literature review work is then bench-marked against these features.
It must be noted that this literature review considers not only recent
studies but studies going as far back as the 1970s and 1980s. Thus the
wide period considered under this study ensures that no appropriate
studies, past or present, around the subject matter are missed out from
the review process. Further, this paper does not consider one specific
type of literature, but examines a diverse range of literature types including ones that cover the academic, public, private, consultancy, and industrial sectors respectively e.g. government documents (such as from the
Environment Agency, SEPA, EPA US), as well as non-government documents, peer review academic research articles, reports, magazines,
websites, and computer models. Some relevant case studies are also
mentioned briefly and in-line with the scope of the paper as explained
later in Section 2.0. It is worth noting that as part of this review process,
the guidance in the form of anecdotal conversations with professionals
and academics in the field was also used to find more appropriate literature in this area.
2. Definitions and scope
From the perspective of landfill risk analysis, the authors describe
a baseline study process as that fundamental and initial stage of a risk
assessment exercise of landfill leachate in which all basic information
and/or data are collected, organised, and analysed. Specifically, in the
case of landfills, the baseline study needs to take account of a wide
range of multi- and inter-disciplinary issues that the authors categorise
into eight groups including: geology, hydrology, hydrogeology, topography, meteorology, geography, human influences, and site management.
Some of these are partly mentioned in some literature (e.g. Environment
Agency, 1999, 2003a; SEPA, 2003 – See Table 2 for more). Fig. 1 broadly
exhibits the position of the baseline study and its eight groups in the
spectrum of subsequent stages of risk assessment. Some examples on
how various aspects of a holistic baseline study would link with various
subsequent parts of landfill risk assessment are indicated in Section 3.2.
It is emphasised that in this paper the term ‘baseline study’ is used (as a
fundamental supporting mechanism in its own right for carrying out
risk assessment), and this term should not be confused with the term
‘baseline risk assessment’. The paper regards baseline study specifically
for landfill risk assessment and Fig. 1 is only to put the discussion of
the paper in perspective. Therefore, implications and iterations of stages
of risk assessment (along with that of baseline study) and other such
details are not in the scope of the paper but for future research and
Landfilling as a waste management option has potential to pollute all
the three main natural factors of the environment which are land/soils,
air, and waters. In scientific terms these are lithosphere, atmosphere,
and hydrosphere, respectively (Butt et al., 2011). Unlike landfill gas
and (more or less) degraded landfill waste, by virtue of its nature, landfill leachate specifically can pollute all of the three aforesaid principal
factors. For instance, leachate vapours or fumes can find their way into
the ambient atmosphere in sufficient amounts to present danger to
human health and the environment, whereas these vapours or fumes
can be containing chemical and/or biological hazards, volatile organics,
etc. Moreover, landfill gas also breaks through from landfill leachate.
Leachate can be an extremely powerful pollutant of water both above
and below ground level – hydrosphere and hydrogeosphere. In addition, leachate contaminants can pollute land/soils as it moves through
the ground either mixed with water or on its own (e.g. through the
unsaturated zone under a landfill). Therefore, in general, landfill
leachate can be seen as a lot more hazardous product of a given landfill than the other two – landfill gas and (more or less degraded)
landfill waste.
Since landfill leachate generally presents a lot more substantial environmental threat as well as given the limitation on time, resources, and
the scale of the work undertaken, this must be noted that main scope of
this research study is only landfill leachate not landfill gas or landfill
T.E. Butt et al. / Environment International 63 (2014) 149–162
Table 2
Literature review examples/case studies: discussing elements of baseline study present and absent. Note: The term ‘elements absent’ implies knowledge gaps and limitations of the research
works carried out and reported to date.
Elements present
Elements absent
Golder Associates, 2002
This publication regards risk assessment only for small and
closed landfills. It briefly mentions hazards and risks in the
context of contamination of groundwater; contamination
of surface water; gas accumulation; and direct exposure to
contaminated soil, sharp objects, or hazardous gases. These
are the only four scenarios, which this publication
addresses very briefly.
Environment Agency, 2007
This guidance, which is one of the most relevant guidance
documents for landfills, addresses the landfill sector in a
very broad sense. It includes a number of very relevant
aspects that can help risk assessment and baseline study
exercises for a given landfill e.g. site investigation,
groundwater protection and hydrogeology, closure and
after closure, landfill engineering, etc.
Environment Agency, 2012
This website of the Environment Agency lists down a
diverse range of guidance documents relevant to all sectors
regulated under EPR (Environmental Protection Regulations)
which also includes the landfill sector. From the risk
assessment perspective, the most relevant guidance is
Environmental Risks Assessment, abbreviated as H1 in the
list. The purpose of the H1 is to assist risk assessors in
explaining and justifying choice of risk control measures
(Environment Agency, 2011a). This document has a
number of annexes and sub-annexes around various
relevant aspects such as landfill itself (Environment
Agency, 2011b), groundwater protection (Environment
Agency, 2011c), hydrogeological risk assessments for
landfills (Environment Agency, 2010), etc.
Unlike the Environment Agency's website of 2012 which is
for various sectors, this website of the Agency is specifically
for the landfill sector. Hence this website contains technical
guidance to help readers to understand the standards that
the Agency wants the landfill sector to achieve when designing
and managing a landfill site. It covers diverse landfill related
subjects such as waste acceptance; monitoring of landfill
leachate, groundwater and surface water; landfill gas; landfill
engineering; landfill permitting and surrender.
This book provides scientific and technical recommendations
to address challenges that risk assessment procedures faces
e.g. lengthy delays in making complex decisions; lack of
data leading to significant uncertainty in risk assessment;
etc. The book embeds various risk assessment concepts
within a broader framework for risk-based decision-making.
This Environment Agency document provides guidelines for
risk assessment of landfill leachate. Hazards are considered
from the perceptive of groundwater as a receptor/target.
Some baseline study modules such as geology and
hydrogeology are briefly addressed. The SEPA document, on
the other hand, in addition to these elements, also briefly
touches upon aspects such as maximum, minimum and most
likely values of various parameters such as leachate quality.
However, as the title of the SEPA document states, the main
focus of this guidance note is not risk assessment of landfill
leachates but the monitoring aspects of landfill leachates,
ground waters and surface waters alike.
This publication is only for closed landfill sites. Both hazard
and risk are together divided into three types namely, physical,
chemical/bio-chemical and physico-chemical. Thus, no
differentiation is made between hazard and risk when using
the above categorisation. A few aspects of some risk analysis
modules (such as hazard identification, concentration
assessment, exposure analysis)
are addressed to a limited extent.
This website of the EPA (Environmental Protection
Agency) lists down a diverse range of guidance
documents relevant to various types and aspects of risk
assessment such as: exposure factors (EPA, 2011);
toxic release inventory (TRI) (EPA, 2010); evaluation of
toxicity of chemicals (EPA, 2009a); development,
This publication is not for presenting a detailed algorithmic,
ready-to-use, sequentially linked, categorical, user-friendly
formatted, continual and step-by-step baseline study system,
which a risk assessor could follow from the start to finish in
a self-guided fashion in order to identify and categorise all
landfill-site characteristics that are needed in different
follow-on stages of a risk assessment for landfill leachate.
All the baseline study elements described in Section 3.2 are
fully or partly absent.
The scope of the guidance document does not include
presentation of a holistic baseline study system which a risk
assessors could use as a ‘one-stop-shop’ for a given landfill
leachate's risk assessment. A range of the baseline study
parameters indicated in the 9 elements given in Section 3.2
(e.g. how to employ statistical considerations to establish
worst-case and most likely scenarios, uncertainty
assessment, etc.) are not included. Moreover, the parameters
which have been included are not laid out in a categorical
and sequential manner so that they could be readily used
by risk assessors using a ‘step-by-step’ approach.
Same as the case of Environment Agency, 2007 (see above).
Environment Agency, 2011d
EPA, 2009d
Environment Agency, 2003a and
SEPA, 2003
CIRIA, 2001
EPA, 2012
Some of various guidance notes on the website address
some aspects which can become part of baseline study for
landfill risk assessment. However, none of the guidance
documents offer a holistic baseline study system which risk
assessors could use as a ‘one-stop-shop’ in a sequential,
categorical and step-by-step manner.
Since the book addresses risk assessment in a broader
context, it is not specifically for risk analysis of landfills and
therefore does not address the issue of holistic baseline
study for risk assessment of landfill leachate,
and therefore does not cover the diverse parameters
indicated in Section 3.2 of the paper.
Apart from some aspects of the baseline study modules
briefly addressed (as mentioned in the left column),
overall all the elements from 1 to 9 in Section 3.2 are either
absent or not addressed sufficiently to a level where they all
could be tied together into an algorithmic procedure of a
quantitative baseline study system.
In-operation and pre-operation landfills are excluded. The
publication is not specifically for landfill leachate. Though
some aspects of risk analysis modules (mentioned in the left
column) are taken into account, the baseline study work
is almost totally missed out for the elements indicated
above in 1 to 9 in Section 3.2.
None of the guidance documents are specifically for risk
assessment of landfill leachate using a holistic baseline
study approach, with all the 9 elements listed in Section 3.2
integrated into it.
T.E. Butt et al. / Environment International 63 (2014) 149–162
Table 2 (continued)
Elements present
EPA, 2012
evaluation and application of environmental models
(EPA, 2009b); dosimetry-based cumulative risk assessment
(EPA, 2009c); cumulative health risk assessment of
multiple chemicals, exposures and effects (EPA, 2008);
and assessment of risks from metals (EPA, 2007).
This publication provides guidelines for characterisation
of municipal solid waste in Portugal. This can be helpful
as a part of baseline study in the Site Management unit
(Section 3.2) where ‘waste types’ is one of the parameters.
This publication is for risk assessment of landfill gas
only. It touches on a range of risk assessment modules
such as gas generation, human exposure, etc.
This publication, which is a research paper, is related
to risk analysis for landfill gas sites. It includes modules
such as exposure assessment, toxicity assessment and
risk estimation.
This document provides generic material for the
development of functional risk assessment guidance
to assist in issues like contaminated land, waste
management, and major accident hazards (DEFRA, 2002).
It examines a range of risk assessment topics such as
dealing with uncertainty, types of quantification, and
evaluation of the significance of a risk. This guidance is
a useful starting point. It serves as the ‘first port of
call’ for many Environment Agency officers, before they
tackle the detailed project work. It can also be used by
anyone else interested in risk-based decision-making
in Government. (DEFRA, 2002).
This landfill risk assessment publication is from the
perspective of issues such as noise, odour, litter,
birds, vermin, insects, and mud on road.
This publication focuses on landfill gas, not leachate.
Martinho et al., 2008
Gregory et al., 1999
Redfearn et al., 2000
DETR et al., 2000
Environment Agency, 2003b
Environment Agency, 2003c
Harris, 1984; Asante-Duah, 1990;
DOE, 1994a; Jones, 1997;
EPA, 2003; Google, 2006;
Arell and Folkes, 2004.
Bernard et al., 1996, 1997
Bardos et al., 2003a, 2003b; SCEG, 2003;
Nathanail and Nathanail, 2003
Environment Agency, 2004
These publications are on a Hazard Ranking System
(HRS) employing a scoring mechanism, which is a
semi-quantitative approach i.e. neither purely
quantitative nor entirely qualitative (Chapman and
Wellington, 2004; EPD, 2004; Lloyd and Wilson, 2002;
Pollard et al., 1995; Robinson, 1999). HRS is a principal
mechanism that the EPA (US) uses to place uncontrolled
waste sites on the National Priorities List (NPL). It is a
numerically based screening system that uses
information from initial, limited investigations – the
preliminary assessment and site inspection – to assess
the relative potential of sites to pose a threat to human
health or the environment.
These two papers (Part 1 and 2) are on hazard analysis
of landfill leachate. They discuss leachates from 25
landfill sites in France as case studies, with a number
of methods of determining leachate toxicity. They then
compare the physico-chemical characteristics of leachates.
These four articles draw on some aspects of hazard
assessment and risk analysis from the perspective of
contaminated land.
This document briefly addresses a broad and diverse
range of facets of landfill risk analysis along social,
technical, environmental, economic, legislative and
managerial themes. Both landfill gas and leachate are
addressed. The main scope of the guidance is limited to
five areas of risk assessment, which are accidents and
their consequences; hydrogeology; landfill gas;
particulate matter; and stability.
Blight and Fourie, 1998
This is only for landfills.
Pollard et al., 2000
This document provides technical guidance to Environment
Agency staff and to applicants on the practical environmental
risk assessment tools that can be used in the waste
management licencing process to assist in the design and
operation of a site. However, it needs to be used alongside
the DETR/EA Guidelines for environmental risk
assessment and management (DETR et al., 2000).
Elements absent
This guidance document does not consider all the other
elements and parameters of the baseline study as indicated
in Section 3.2
Landfill leachate is not included in this publication. Thus,
the elements from 1 to 9 (listed in Section 3.2) are
completely absent from the landfill leachate perspective.
A detailed baseline study is not within the scope of this
publication. All the elements from 1 to 9 (Section 3.2)
are absent in the context of landfill leachate.
This publication addresses a range of risk analysis issues
in general (listed in the left column). However, the focus
of this work is not specifically on landfill leachate, but
rather on a host of environmental hazard issues. Therefore,
it is too generic to be of specific use. Moreover, the
document does not address the baseline study factors
indicated in points 1 to 8 of Section 3.2 which are strictly
related to landfill leachate.
The publication is not about landfill leachate in the first
place. The elements 1 to 9 are totally absent.
Even for landfill gas issue, the baseline study elements 1 to
9 (Section 3.2) are not addressed in an integrated manner.
The HRS does not offer a holistic baseline study methodology
for landfill leachate. Also specifically from the perspective of
landfill leachate, the elements from 1 to 9 mentioned in
Section 3.2 are absent in the HRS approach.
These publications do not present a strategic baseline study
framework comprising the 9 elements (depicted in
Section 3.2) for landfill leachate.
These articles do not specifically address the baseline study of
landfill risk assessments and all the 9 elements (Section 3.2)
are absent from the perspective of landfill leachate.
As the document states itself that there are five main
areas, which constitute the main scope of the guidance
(listed in the left column). Yet landfill leachate is not one
of them, though is addressed to a limited extent. The
guidance also mentions that it does not provide all the
detail needed to conduct risk analysis for a landfill site.
Although some baseline study modules such as
hydrogeology are included while others like meteorology,
human influence and geography are not addressed. Overall,
a holistic baseline study is not in the scope of this publication.
This study very briefly outlines the requirements when
carrying out a baseline study. However, there is no evidence
of a strategic and systematic methodology for a baseline study
encapsulating all the elements indicated and described
in Section 3.2.
Although, this document introduces the concept and stages
of environmental risk assessment, it does not offer a holistic
baseline study methodology specifically for landfill leachate
(continued on next page)
T.E. Butt et al. / Environment International 63 (2014) 149–162
Table 2 (continued)
Elements present
Elements absent
EPD, 1997
This publication is a guideline for hazard analysis of
landfill gas. It briefly covers various aspects of hazard and
risk assessment such as hazard mitigation measures and
the source-pathway-target analysis approach.
ICRP, 1975; ICRCL, 1987;
Eisenbeis et al., 1986; OSHA, 1989;
Johannsen, 1990; Montague, 1991;
Kavazanjian et al., 1995;
Jaggy, 1996; Asante-Duah, 1996;
ICE, 1994; WDA, 1994;
Pieper et al., 1997; Senior, 1995;
DoE, 1986, 1991, 1993, 1995a;
CIRIA, 1993, 1995.
Some old literature (with examples given in the left
column) regarding landfill assessment, in particular, and
other risk assessment procedures, in general, were also
extensively studied to ensure that no historical work
was carried out in the area of the development of a
holistic framework for baseline study and risk analysis.
The literature was found to address various risk
assessment issues like seismic hazard analysis for landfills;
carcinogenic and non-carcinogenic risks; air contamination;
landfills' leakage; exposure assessment; baseline study;
toxicity assessment; risk estimation; specific landfill
types and nature; radiation; contaminated land remediation;
specific hazards such as polychlorinated dibenzo-p-dioxins
and furans (PCDD/F); landfill microbiology; landfill gas;
landfill completion; landfill design and construction aspects.
This publication relates to exposure assessment for humans
from contaminated lands. Details on various aspects of
exposure assessment are given. Examples include exposure
parameters (such as exposure duration, frequency), soil
release and transfer mechanisms, exposure equations,
human activities and ages, exposure routes, and various
These publications are specifically for landfill leachate and
focuses on the exposure assessment and hazards'
concentration assessment sections of a total risk assessment
system respectively. An integrated and quantitative model
of exposure analysis is presented and some links are also
drawn with the relevant parts of a baseline study.
The study focuses on one type of hazard i.e. particulate
matter (PM) and only in air as an exposure medium. The
only exposure route accounted for is inhalation, and this
work only considers humans as receptors.
This document can contribute to a landfill risk assessment
in terms of exposure analysis. This publication portrays
exposure assessment in a more complete manner than any
other literature studied to date. The focus is not on
environmental receptors but on only human health.
Similarly, not all potential exposure pathways have been
included, but only the six which cover most risk to human
health from landfills.
A procedure on exposure assessment has been outlined
and only humans have been considered as receptors.
This study only addresses the exposure analysis aspects,
and of that, only the chemicals issues.
The publication is not for landfill leachate. Even for landfill
gas, the elements from 1 to 9 (Section 3.2) are either
completely absent or are only covered in a cursory manner
(as described in the left column). However, from the specific
leachate point of view, all the 9 elements are totally absent.
None of these publications (including the ones which are
specifically for landfills) offer a categorical and sequential
procedure for the baseline study of landfill leachate in a
holistic manner. For instance, ICE's work of 1994, even
though it touches upon a baseline study to a degree, but
focuses instead on contaminated land rather than specifically
on landfill leachate. Similarly, Asante-Duah (1996) describes
all the important aspects of risk analysis including baseline
study but not in the form of an integrated methodology.
His work is rather an independent analysis of each in
different individual chapters. In summary, all the elements
from 1 to 9 (listed in Section 3.2), have not been tied
together in an algorithmic format either for landfill leachate
or for that matter in regard to any other environmental issue.
As the title of the publication states that the focus of the
publication is exposure analyses, thus a baseline study has
not been addressed as such. Moreover,
it is for contaminated
land in general and not landfill leachate specifically.
DEFRA and Environment Agency, 2002
Butt et al., 2011; Butt and Oduyemi, 2003
Moschandreas et al., 2002
DoE, 1995b
Eduljee, 1998
Daugherty, 1998
EPA, 1992, 1999
SEPA, 2002
These publications purely consider exposure assessment.
However they cover the subject from many different
perspectives including types of hazards, pathways,
receptors and exposure; also, types of dose, (e.g. potential
dose, intake dose, applied dose, etc.), exposure dose
relationships, uncertainty assessment, individual and
population exposure, exposure analysis in epidemiological
studies, and the position of the exposure assessment
itself with respect to risk characterisation.
This publication regards landfill risk assessment in the
context of landfill leachate liners and drainage systems.
CPPD, 2004
This publication is in draft form only. It regards hazard and
risk assessment in the context of natural hazards such as
flooding, earthquakes, landslides, and wildfires.
Rudland et al., 2001
This work describes a basic framework for risk analyses of
contaminated land.
Auckland Regional Council, 2002
This publication, which is a government document for
local authorities, covers risk assessment in a very broad
sense when regarding hazard. These include natural
hazard such as tornadoes, flooding, earthquakes;
technological hazard like high pressure gas mains
The baseline study system is not within the scope of the
publication. Thus, all the 9 elements (Section 3.2) are absent.
The publication does not present baseline study procedures.
This publication is not specifically for landfills.
This publication does not offer a holistic baseline study for
landfill leachate that could readily be used in conjunction
with a landfill risk assessment process. In summary, all the
elements above from 1 to 9 are absent.
Same comments as DoE, 1995b above.
This study is not specifically for landfills, and therefore there
is no holistic baseline study procedure covered in the
publication, even if only the chemicals issues are considered.
These documents do not portray a holistic procedure for
carrying out baseline study either specifically for landfills or
for any other environmental risk analysis scenario. When
considering the landfill perspective All the 9 elements
(in Section 3.2) are absent in these publications.
Apart from the aspect of liners and drainage systems, which
can form part of a site management module of a baseline
study, the elements from 1 to 9 (in Section 3.2) are not
fully present.
The publication is not for anthropogenic activities, and
therefore does not consider landfills. The document only
discusses various natural hazards and provides statistics on
them, but does not present a structured baseline study
procedure even for these natural hazards listed in the
adjacent column.
This work is not specifically for landfills. Hence all the
elements from 1 to 9 (in Section 3.2) are absent in the
context of landfill leachate.
This publication is not specifically for landfills. It just
encapsulates all natural as well as anthropogenic hazards
without presenting a holistic baseline study procedure.
The format is more like a checklist. Thus, the entire
baseline study elements from 1 to 9 (considered in Section3.2)
T.E. Butt et al. / Environment International 63 (2014) 149–162
Table 2 (continued)
Elements present
Auckland Regional Council, 2002
failure, or computer systems failure; biological hazard
including disease among people, animals or plants; and
civil/political hazard comprising terrorism activities
and civil unrest.
The focus of this work is landfill gas and also that of a
specific landfill site.
Scott Wilson (Hong Kong) Ltd. (1997)
Environment Agency, 1997
DOE, 1998
EPA, 1988, 1996a, 1996b, 1996c, 1998
This document addresses risk assessment from the
perspective of human health only as a receptor, and
only for those landfills which have as a pollutant source
contaminates from house hold waste.
This environmental guidance document mentions
Risk-Based Corrective Action (RBCA) standards that were
developed for addressing petroleum and chemical
release. The purpose of this guide is to explain
risk-based decision making and the RBCA process for
environmental restoration of chemically contaminated
The first four documents consider risk assessment of
neurotoxicity, reproductive toxicity, ecology and
carcinogens respectively. The fifth publication is on the
evaluation of the potential carcinogenicity of Acrylonitrile.
Government of Western Australia, 2009
This report is specifically on the baseline study of
contaminants in groundwater carried out specifically
for disused waste disposal sites in the Swan Canning
catchment area in Australia.
Hokkanen and Salminen, 1997
This research work addresses a broad range of waste
management options including landfills, composting,
incineration, and transport issues.
The main theme of the paper is waste production,
recycling and disposal.
This paper discusses various risk assessment tools and
how to select a specific tool for a specific scenario based
on the following:
(i) the appropriate tool by reference to the
type of risk problem under study; and
(ii) the appropriate level of sophistication
selected as needs, complexities,
priorities and data allowance.
This paper addresses a range of waste management
options including landfills, incineration, compost
and sewage.
The focus of this publication is the characterisation of
waste from different perspectives such as recycling.
Chowdhury, 2009
Pollard et al., 2006
Giusti, 2009
Loughborough University, 2006
Villanueva et al., 2009
This paper considers a process-based waste management
system and uses a Parisian case study.
CMSA, 2004; Puncochar, 2003;
Koivisto et al., 2001; Feldman and White,
1996; CHEM Unit, 2003; Pauluhn, 1999;
PDC, 2003; Thatcher, 2002; EPA, 2002;
Hull et al., 2002; HCPC, 2004;
Catlin et al., 2001; Hoffman et al., 2003;
Kinsman and Maddison, 2001; Hekster
and de Voogt, 2002; DOE, 1993, 1994b;
Brown, 2000; Norton, 2002; QUT, 2004;
Keith et al., 1999; Tarazona, et al., 2000;
Fleming and Fleming, 2002; A-NPDC,
2004; Anderson and Albert, 1999;
Jones et al., 2004; Karvonen, 2000;
Brown and Stringer, 2002; Ochola et al.,
2002; DEM, 2004; Sanchez and Burger,
1998; UCL, 2002; Gillanders, 2003;
Crawford-Brown and Brown, 1997;
Chen et al., 1998; HSE, 1998; Pease,
1992; Muth et al., 2001; Tarazona and
Vega, 2002; DHS et al., 2009;
Wessberg et al., 2008; Pollard et al.,
2004; EPA, 2000b; McKenna, 1998
These publications focus on hazard and risk assessment
for when considering the following subjects: mining, the
workplace, genetically modified organisms, neurology,
the indoor environment, ecology, toxicology, software
systems, wildlife, terrorism and safety issues, human
health and epidemiology, aquatic chemistry and aquatic
toxicology, seismology, natural hazards (like drought,
wildfires/forest fires, storms, etc.), explosions,
ecotoxicology, fires in agrochemical warehouses,
aquatic environments, human health, contaminated land,
food safety, health and safety systems, radiation, terrestrial
environments, energy and electricity, shore environments,
air quality, cattle importation, the economy, microbiology,
farming machinery, nuclear production sites, educational
establishments, project management systems,
carcinogenicity, petroleum contamination, offshore
installations and the oil industry, regulations development,
food issues, chemicals and eco-systems, information
technology, accidental emissions, water utilities,
chemical mixtures, and hormesis.
Elements absent
are absent not only for landfill sites but also when considering
any general hazards.
This study does not offer a baseline study system
comprising features 1 to 9 (in Section 3.2) for landfill
leachate, and in a similar manner not even for landfill
gas production.
This work does not present a baseline study methodology
encompassing the aspects listed in Section 3.2 for landfill
The purpose of this document is not to present a strategic
and integrated baseline study framework, and specifically
does not consider landfill leachate. The system described
is more over only used to determine the data requirements
needed for technical decision making, rather than focusing
on the specific process steps needed for a risk analysis,
or when conducting a baseline study.
These documents may indirectly be useful in risk analysis
of landfill leachate in the context of establishing
neurotoxicity, reproductive toxicity, ecological and
carcinogenic affects of leachate pollutants. However, these
publications are not produced from the point of view
of landfill leachate and thus, in this sense all the baseline
study elements from 1 to 9 (in Section 3.2) are absent.
As already mentioned in the adjacent column, this
document only considers a specific case, and therefore
does not present a holistic baseline study system (with
the 9 elements given in Section 3.2) that could be readily
useable for other landfill scenarios.
This publication does not consider the holistic baseline
study systems specific to landfill leachate.
This paper does not cover risk assessment or the baseline
study part of risk analysis.
The scope of this paper does not cover the presentation
of a holistic baseline study framework specific to
landfill leachate.
This paper is not meant for the development of a baseline
study methodology that could constitute a risk assessment
system specific to landfill leachate.
This publication is not for risk assessment of landfill leachate,
and thus there is no description of a baseline study
framework for risk assessment specific to landfill leachate.
The scope of this paper does not address a baseline study
procedure connected to a risk assessment of landfill leachate.
Thus, the publication does not contain a holistic baseline
study framework, and all the elements listed in Section 3.2
are absent.
These publications address the risk assessment context in a
diverse range of fields and they all need a holistic baseline
study system specific to each area. However, none of these
publications are useful for landfill sites.
T.E. Butt et al. / Environment International 63 (2014) 149–162
Risk Assessment / Analysis
Human influences
Site management
Fig. 1. The baseline study modules and its position in relation to overall risk assessment structure (adapted, derived and concluded from the work of various authors including CIRIA, 2001;
CMSA, 2004; Environment Agency, 2003a; EPA, 2000a; Peacock and Whyte, 1992; TOSC, 2000; Viswanathan et al., 2002; WDA, 1994).
waste. A cut off had to be drawn to define the manageable size of the
study and the word ‘holistic’ is used specifically within this scope
which is landfill leachate. Therefore, it is worth mentioning that the
term ‘holistic’ in this paper implies an overall framework with a wholesystem and unified approach (Arquette et al., 2002; Aven and
Kristensen, 2005) that covers all aspects and factors of the baseline
study (See Section 3.2) from the start to end in the context of landfill
leachate only – neither landfill gas nor (more or less) degraded landfill
waste, as the inclusion of these two would have grown the paper
beyond limits and the depth of study specifically around landfill leachate
alone was going to be compromised.
The term ‘holistic’ not only means ‘inclusiveness’ and ‘comprehensiveness’ but also implies ‘appropriate integration’ of and ‘linking’ between
these aspects and factors (Section 3.2) in an algorithmic, coherent, consistent, and sequential manner so that these could logically and systematically be referred to in the later stages of a risk assessment process. This
is in line with the general principle of ‘holism’ or ‘wholism’ as concisely
summarized by Aristotle in the Metaphysics: “The whole is more than
the sum of its parts” – where the word holistic or holism comes from
a Greek word ‘holos’ which means ‘all’, ‘entire’ or ‘total’ (Ask Define,
2013; Environment, 2013; Philosophy Basics, 2013; Sobel, 2010). The
idea is that all properties of (a baseline study) system cannot be determined or explained by its component and sub-component parts alone
(Section 3.2). Instead, the system as a whole determines an important
way of how the parts behave and can be effectively and efficiently used
in the subsequent stages of a risk assessment exercise of landfill leachate.
This is the context in which the term holistic or holism has been deployed
in the paper. Furthermore, in order to establish what crucial parts a holistic baseline study system (specifically for landfill leachate) is supposed to
be composed of, not only ‘holism’ theme but the ‘reductionism’ theme has
also been employed (Environment, 2013). In other words, ‘synthesis’ and
‘analysis’ have been used in the study.
3. Baseline study and risk assessment
3.1. Risk assessment — connection with baseline study in the holism context
The review of environment-related literature clearly shows that a
baseline study is a crucial and primary factor in an environmental risk
analysis. Moreover, the investigation (contained Table 2) led to the
conclusion that a comprehensive, robust, detailed, and sound risk
assessment methodology, incorporating a number of essential features
(including that of baseline study) does not exist in an integrated
manner. Examples of essential features are:
• Encompassing various types of landfill systems and their surroundings
(hydrosphere, atmosphere, geosphere, and any combination of these
e.g. hydrogeosphere);
• Taking into account all possible characteristics of landfills in terms of
risks and quantification of risks posed by landfills including statistical
descriptions such as maximum minimum, and most likely values;
• Encapsulating other features and scenarios that render a risk analysis
more comprehensive such as uncertainty assessment and significance
assessment; and
• Embedding procedures of relevant individual modules (such as hazard
identification, hazard concentration assessment, exposure analysis and
quantification, pollutants migration, and baseline study).
Inconsistency in risk assessments is an important issue, not only for
the government sector (e.g. the Environment Agency and SEPA – who
are environmental regulators) but also the commercial sector including
environmental (risk) consultants and the landfill industry – who have
to produce site-specific risk assessment reports for environmental
regulators (Booth and Jacobson, 1992; Buss et al., 2004; Environment
Agency, 2007; SEPA, 2011). Irrespective of quality of site-specific data
and variation in style and expertise of regulators and consultants,
one of the most significant reasons of inconsistency is no two landfill
scenarios are the same. Characteristics of landfill scenarios may vary
widely from one to another, not only in terms of a landfill itself and its
management practices but also the setting around it e.g. diversity of
receptors, and pathways. Therefore, a holistic risk assessment system
is required which encapsulates all possible characteristics, features,
aspects and factors in one place – under one ‘umbrella’ – in which risk
assessors could use to appropriately choose from and even be able to
explain what has not been included and why. This is not to be merely
a check list of items but also a complete set of guiding principles of
how, when, where and why various items of risk assessment interact
with each other and what needs to be included (or even excluded)
with justifications for a given risk assessment scenario. To help solve
the issue of inconsistency and lack of holism in risk assessments, a holistic baseline study can be effectively useful. In other words, a consistent
and coherent baseline study system is one of the crucial requirements to
generate consistent and coherent risk assessments. This is explained
further in Section 3.2. Since inconsistency among risk assessments also
leads to compromise the degree of risk comparisons, therefore, consistency in risk assessments can help the issue of risk comparisons between two or more landfill scenarios in a number of ways e.g. where a
new landfill can more safely be sited. Thus, a consistent baseline study
system can also be useful in this regard.
Furthermore, landfill leachate is a multi-dimensional pollutant source
that can (either directly or indirectly) pollute lithosphere, atmosphere,
hydrosphere, and even any combination of these (details in Section 2.0,
paragraph 2). As individuals, these three entities are not only fundamental constituents of the environment but also principal media of transmission of contaminants. Therefore a more comprehensive, concise, and
robust risk analysis system, underpinned by a correspondingly more strategic baseline study system, will be needed. Furthermore, the environment legislation has also been growing stringent as well as holistic
(as explained in Section 3.3 and Table 1) which is requiring risk
assessments to be increasingly integrated and unified.
Therefore, in order to render a risk assessment holistic, a correspondingly holistic baseline study system will be required for a baseline
study lays bases of subsequent stages of a risk assessment in a given
scenario (see Fig. 1 which is an indicative of risk analysis steps). If the
T.E. Butt et al. / Environment International 63 (2014) 149–162
baseline study system is not lacking holism and is unified, consistent,
and integrated, then so will more likely be the risk assessment which
is primarily based on the good and appropriate quality of the baseline
study – the foundation. However, the main focus of this study is the
baseline study itself as a system and not the risk assessment as such,
therefore the following section purely addresses the baseline study
and in more detail.
3.2. Baseline study — in the holism perspective
A comprehensive review of risk assessments currently used for environmental management highlights clearly that there is currently a lack
of an integrated procedure for carrying out baseline study in various
environmental fields, and especially in landfill leachate management.
Although a great deal of research on risk-based approach in a number
of environmental fields (including landfill waste management) has
been carried out (See Table 2), none of the studies appear to have
addressed specifically landfill leachate via developing a holistic baseline
study system.
In order to support risk assessments specifically in relation to landfill
leachate, a list of a number of elements or features are indicated
below that need to be drawn together in a sequential and algorithmic
manner to form a holistic – a consistent, coherent, and yet wholesystem – architecture of baseline study. However, details on how these
elements should be assembled together to construct the holistic baseline
study's architecture are not within the scope of this study. Based on extensive literature review, the study is to identify what knowledge gaps
exist in the state-of-the-art of baseline study, and only indicatively mention why and how these gaps can be bridged. Where appropriate, the
paper still points out relationships of the below-listed elements of the
baseline study system not only among themselves but also with the
other parts of risk assessment, and an indicative framework of a
holistic baseline study is shown in Fig. 1. An exhaustive study of literature is contained in Table 2, which establishes that these below-listed elements are either entirely or partly absent in current approaches and
1. Keeping in view the multi- and inter-disciplinary nature of a baseline
study for landfill leachate, the authors divide it into eight modules
that are listed below with examples of parameters which these
modules can take into account. Current baseline study approaches
for risk assessments are found not to have included all of these
eight aspects in an integrated manner.
i. Geology: top soil, drift, rock, porosity, effective porosity, fissures,
density, geological materials and minerals, depth and width or
volume of the geological materials, and other geological properties.
ii. Hydrology: evaporation, transpiration, interception, surface runoff,
infiltration, percolation, and groundwater ingress.
iii. Hydrogeology: vadose and phreatic (also called unsaturated
and saturated) zones, perched groundwater, hydraulic gradient, permeability, groundwater speed and direction, and other
hydrogeological properties.
iv. Topography: landforms and inclinations (to assist in measuring
runoff to or from a given landfill), natural environment, habitats,
built environment, water-courses, etc.
v. Geography: latitudes, longitudes, geographic zones (e.g. tropical
and other geographic properties that can also help in estimating
other baseline study parameters such as expected rainfall).
vi. Meteorology: precipitation (duration, frequency, intensity), wind
speed and direction, wet and dry bulb temperatures, humidity,
and degree of sunniness and cloudiness. Factors like wind, temperature, and humidity can also help with establishing degree
of formation of leachate vapours or fumes.
vii. Human influences: past, present, or future potential anthropogenic activities (like quarrying, water abstraction, construction,
and development).
viii. Site management: site history, site type, site location, site design
and engineering (e.g. liners, drainage system), site surface
area, waste management activities, waste types, environmental
monitoring, leachate collection system, leachate management
2. The authors do not find evidence of a detailed, algorithmic, readyto-use, sequentially-linked, categorical, user-friendly-formatted,
continual, and step-by-step baseline study system, which a risk
assessor could follow from start to end in a self-guided fashion
to identify and categorise all landfill site characteristics that are
needed in different subsequent stages of a risk assessment process
for landfill leachate.
3. There is a lack of ‘significance assessment’ of all baseline study
parameters and their characteristics. For instance, what conservative
measures are taken – and for which parameters and why? Is the
amount of interception for a given landfill significant enough to consider in leachate quantity measurement? Is the quantity of liquid
waste small enough to be ignored in the water budget equation of
the landfill on annual basis? Etc.
4. There is a deficiency of ‘uncertainty assessment’ of all baseline
study parameters and their characteristics, where these uncertainties could be due to estimation methods, lack of knowledge,
data quality, etc.
5. No appropriate consideration has been given to the format and
means of data collation at baseline study stage that could assist in
working out worst-case and most-likely risk scenarios in subsequent
stages of a risk assessment process. Such means are indicated in
points 6, 7, and 8 below:
6. Employment of statistical descriptions lacks particularly in the
context of maximum, minimum, and most-likely values of various
parameters (e.g. evapotranspiration, precipitation, interception, and
groundwater ingress). Such statistical descriptions can be helpful to
figure out worst-case and most-likely risk scenarios; as well as to
address uncertainties, and temporal and spatial variations.
7. There seems to be a deficiency of appropriate consideration of temporal and spatial variations of various parameters of the baseline
study. For instance, temporal variation of leachate quality in terms
of its becoming mature over time; spatial variation of the unsaturated
zone underneath a given landfill in order to figure out effective
vadose thickness; etc.
8. For risk assessment to be quantitative, all appropriate parameters of
the baseline study need to be quantified. Examples of such parameters
are interception, precipitation, and groundwater ingress. The more the
objective measurement of such parameters is, the more successful the
quantification of the associated risks will be.
9. A given landfill can be at pre-operation stage (i.e. planning, design,
and development phase), in-operation stage, and/or post-operation
stage (i.e. completed and post closure phase). In the current baseline
study approaches, there is a lack of consideration of the issues
regarding the three landfill stages taken together.
In order to integrate all these elements there is a need for a comprehensive, algorithmic, and systematic baseline study framework which
could provide guidelines on acquiring, sorting, and analysing all the
data and/or information of preliminary investigation of a given landfill
in such a useful format which could be systematically related to the subsequent stages of the risk analysis.
A number of case studies have also been considered as a part of the
literature review. No case of landfill risk assessment was found to have
considered a baseline study in a holistic and integrated manner with all
the elements described above. It has been noticed that only a few of the
aforesaid aspects of the baseline study are variably taken into account.
For instance, groundwater, rainfall and locations of nearby surface
water courses were among the main parts of the baseline study carried
out in the assessment of contamination of the Swan Canning River
system by landfill leachate (SRT, 2009). But the baseline study process
T.E. Butt et al. / Environment International 63 (2014) 149–162
in this case study did not consider all the aforesaid listed 9 elements in a
holistic and categorical fashion. As for other case studies, in some cases
landfill liners, capping, and site area were main considerations
(Depountis et al., 2009; Ganatsiou, 2006) which can only become part
of 1-viii above; some cases focused on communities' distance and direction from landfills (e.g. Sarkar et al., 2003) – which can contribute to the
topography section of the baseline study; others considered environmental monitoring of leachate (e.g. Abu-Zeid et al., 2004) which can
feed into the site management section of the baseline study; some
cases took account of soil stratigraphy of landfill sites (e.g. Aderemi
et al., 2011) – which can constitute geology section of the baseline
study. Similarly, landfill risk assessment models (such as LandSim and
HELP) address the baseline study predominantly in the hydrogeological
context along with other associated aspects (Environment Agency,
2003d; Golder Associates, 2012; SSG, 2012) but not include all the 9
elements listed above in a categorically systematic manner. Thus, different case studies of landfill assessments have appeared to account for
different aspects of baseline study. In a way, they contain a ‘mix and
match’ of various baseline study elements and aspects (listed above),
and none presents or applies a holistic baseline study system. One simple
reason for this is that there is no such holistic system in place.
There are a number of future needs of risk analysis that are required
in order to respond to the new waste and resource management agenda
(Pollard et al., 2006), and holistic baseline study for landfill leachate risk
assessment is one of them – where a holistic baseline study system
includes not only the eight modules indicated in Fig. 1 but also other
aspects listed in Section 3.2 of the paper. With the way in which environmental legislation is becoming more integrated and inclusive
(Section 3.3), current non-holistic and non-integrated baseline study
approaches are not going to be sufficient in the future to carry out landfill risk assessments with satisfactory level of completeness.
3.3. Current and future legislation
With reference to the ‘state-of-the-art’ (indicated in Table 2), the
current procedures used regarding risk analysis and baseline study, particularly for landfill, appear to be just sufficient to meet the current legislation requirements (such as drinking water standards). The literature
review reveals that predominantly only humans have been considered
as receptors (See Table 2). There is clearly a lack of attention given to
other potential receptors in a holistic manner, for instance:
• Receptors other than humans such as aquatic and terrestrial flora and
fauna (e.g. crops and fish);
• Natural environment consisting of various environmental media
(e.g. land/soil, air, watercourses/groundwater);
• Built environment comprising human-made ponds, buildings, residential houses, utility networks, playgrounds, entertainment centres,
• Water courses, other than those used by humans for drinking, such as
rivers of various water grades (SI, 1994b); and
• Insufficient consideration of multiple exposure routes and multiple
exposure media of landfill leachate (such as dermal contact, fish contamination, bioaccumulation in plants, and food-web chain).
The features listed above in Sections 3.1 and 3.2 become increasingly
more important, both individually as well as collectively, when considering the implementation of new environmental ‘legislative instruments’
that nowadays already are and also are becoming more stringent, versatile, inclusive, and integrated. For instance, with reference to Table 1, the
Water Framework Directive (EC, 2000), which has been employed in the
UK, includes new requirements for protection and restoration not only of
ground waters but also surface waters and their dependent ecological
systems (Environment Agency, 2003a). Another directive, which is generally referred to as the ‘Habitat Directive’ (EC, 1992), specifies a legal obligation to combat hazards in order to guard and enhance natural habitats
and wild fauna and flora. The Landfill Directive emphasises protection of
not only hydrosphere, but also lithosphere, and atmosphere (i.e. quality
of waters, soils and air is to be collectively guarded from landfill pollution). Thus, a more inclusive and integrated approach towards risk analysis is required. This requires that a baseline study be more integrated and
strategic, as without a holistic baseline study, a complete risk analysis is
not possible.
Although these directives appear to be relatively old but it takes
years for them to filter down, be interpreted and then implemented
by member states. This also includes transitional periods and intermediate phases of implementation. Thus, all this takes substantial amount of
time. These directives have been and are being implemented via a range
of new regulations and guidance documents (e.g. DEFRA et al., 2011,
Version 3.2, page 3). Whereas, old regulations are continually being
revised based on feedback from consultancy, industrial and public/
government sectors, and other appropriate stakeholders. For example:
Environmental Permitting Regulations 2007 (SI, 2007) was revised by
the 2010 version (SI, 2010), which has now been even further upgraded
by the Amendment Regulations (SI, 2011); similarly the oldest version
of Waste Management Licensing Regulations was 1994 (SI, 1994a) and
the latest so far is the 2005 regulations (SI, 2005); the Groundwater
Regulations 1998 (SI, 1998) has now become the Groundwater Regulations 2009 (SI, 2009).
4. Concluding discussion
While the current and forthcoming legislation pushes forward to
reduce both the quantity of disposed wastes and the environmental impacts of landfill sites, there is still need to manage the current landfill
sites and find solutions to remediate and control environmental pollution from these sites. Furthermore according to the sustainable Waste
Hierarchy, although waste amounts are to be reduced that are disposed
of at landfills, it is still not possible to have a ‘no-landfill’ society for a
number of reasons: for instance, waste production cannot be reduced
to zero in every scenario. Commodities cannot be reused and/or recycled
all the time e.g. paper after recycling a number of times becomes nonrecyclable as paper fibres deteriorate every time it is recycled. Not all
waste can be composted or incinerated. Even the incineration of wastes
leads to other wastes (e.g. ashes) being generated (though in much
reduced amounts), which generally end up in landfill. Thus, landfill is
inevitable. In other words, number of landfill sites may be reduced via
efficient waste management but not as low as zero to deliver a totally
‘landfill-free’ environment or a ‘zero-landfill’ society. Thus, despite
having potential to pollute the environment, landfill is not entirely
avoidable: some sites are necessary. Therefore risk assessment is necessary as an effective tool to guard the environment against landfill
To the contrary, there does not exist as such an integrated and unified methodology of landfill risk analysis, which could assist performing
the process of risk assessment for landfill leachate from the start
(i.e. baseline study) through to the end (i.e. hazard indices and risk
quantification) – See Fig. 1. A number of knowledge gaps have been
identified in the literature reviewed to date and a holistic baseline
study system is one of them.
The baseline study is not only the most significant factor but also the
most fundamental initial stage of an effective risk analysis, as the success of the latter is based on the former. The paper has established this
not only by defining the baseline study in landfill leachate context but
also indicating implications and scope of the baseline study. The adequacy of a baseline study lies in effectively generating a holistic foundation consisting of relevant data and information to support a specific
risk assessment. This needs to be done as quantitatively as possible to
characterise a given landfill and constitute quantitative aspects of the
risk assessment. This data and information for a specific landfill be collected and organised (i.e. collated) in such a format that the contents
of the baseline study are systematically and categorically laid down to
readily correspond to the following stages of the risk analysis process
T.E. Butt et al. / Environment International 63 (2014) 149–162
of the landfill. The main conclusion of the overall assessment of the literature is that such a baseline study methodology (or even a complete
guidance note) in such an algorithmic format does not exist that could
be used as a ‘one-stop-shop’ by landfill risk assessors.
Current risk analysis approaches are just adequate to meet the
criteria and standards of the present environmental legislation, particularly in the UK. Legislation is increasingly growing to be more stringent
and also wider in scope to encapsulate more environmental aspects and
species (such as various food chain links, ecological systems, terrestrial
and aquatic flora and fauna). Furthermore, landfill leachate has great
potential to (either directly or indirectly) pollute lithosphere (land/
soils), atmosphere (air), hydrosphere (water), and even any combination of these. These three fundamental constituents of the environment
are also the main media of contaminants transport. Therefore a more
comprehensive, concise, and robust risk analysis system – covering
these three principal media – is required. This necessitates a correspondingly more strategic baseline study system with a wide ranging
elements and features (indicated in Section 3.2).
Via an exhaustive literature review as evident from the referent list,
this paper recognises the need and significance of baseline study as a
whole-system approach and identifies knowledge gaps. Although it is
not in the scope of the study to develop a full-on baseline study system
in a holistic manner, still the paper outlines bases for developing an algorithmic framework of such a holistic baseline study procedure which
is integrated, coherent, comprehensive, inclusive, unified, sequential,
offers consistency, and yet particularly for landfill leachate. The paper
clearly lists downwide-ranging elements and features that need to be
drawn together in order to form such a whole-system architecture of
baseline study in the future. This way the paper paves a path for further
research and development in the field of risk assessment, specifically in
connection to baseline study.
The authors acknowledge the financial support of Dundee City
Council which made this research study possible. We are additionally
grateful for the discussion and help received from Mr Peter Goldie of
the Environment & Consumer Protection Department, Dundee City
Council. The support from Mr Stephen T. Washburn (CEO, ENVIRON,
New Jersey, US), Dr I. M. Spence (Consultant Environmental Geologist,
Scotland), and colleagues at the University of Abertay Dundee, including
Dr Olisanwendu Ogwuda, Dr Kehinde O. K. Oduyemi, and Mr Phillip
Jenkins is also highly appreciated. It must be noted that concepts and
ideas presented in this article by the authors do not necessarily represent views that of their respective employer organizations.
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